haevey



UNITED STATES PATENT OFFICE.

H. A. HARVEY, OF NEW YORK, N. Y.

MACHINE FOR THREADING SCREWS.

Specification forming part of Letters Patent No. 51,179, dated November28, 1865.

To all whom it may concern:

Be it known that I, H. A. HARVEY, of the city, county, and State of NewYork, have invented a new and useful Improvement in Machinery forThreading Screws; and I do hereby declare that the following, taken inconnection with the drawings, is a full, clear, and exact descriptionthereof'.

In the drawings, Figure l is an elevation of a machine embodying myimprovements. Fig. 2 is a plan of the same, and Figs. 3 and 4 arevertical sections through the same in thelines a b a b e d e d of Figs.l and 2.

The improvement which constitutes the subject-matter of my presentinvention is a combination of mechanical devices by means of which themotions ofthe chaser are governed or controlled in such manner as tocause it to cnt a succession of cuts upon a screw-blank, and thiscombination governs the chaser in a more firm and exact manner, andaffords better and easier means of adjustment, and of alteration of thesame machine to thread screws of various sizes than other mechanicaldevices employed for the same purpose heretofore.

In the machine shown in the drawings there is a bed-plate, e, tittedwith proper standards for supporting the whole of the machinery. Inthese standards are mounted a driving-shaft, f, which also rotates thechaps or holder which supports the blank to be threaded. This shaftcarries a pinion, f which engages with a wheel, g', upon a shaft, g,upon which is mounted the cam, g2, that causes the chaser or chasingtool'to travel along the blank from the head toward the point of the screw.This same shaft also carries the pinion g3 which gives motion to thecog-wheel h upon the shaft L, which supports the pinion h2, which is ingear with the cogwheel 7c upon the cam-shaft k. Upon lthis shaft ismounted a cam, k2. When the driving-shaft is put in motion, thescrew-blank will revolve and also both ot the cams g2 and k2.

A wedge, Z, is mounted in proper ways or slides so that it may move toand fro in the direction ofthe axis ofthe blank, or nearly so, and thiswedge is forced to travel in one direction by the cam 7a2 acting uponahanger, l', attached to or making part of the slide, and in the otherdirection by a spring, Z2, surrounding a pin attached to the hanger.This spring bears at one end against the hanger, and at the other endagainst a standard, through wlnch the pin slides. This spring causes thehanger to bear against the cam and moves the wedge in a direction fromthe head toward the point of the screw-blank when the cam permits it todo so. This wedge bears against one side of a .mold or former, m, whichis fitted in proper guides, and is free to travel toward and away fromthe screw-blank. This former, whose acting-face m m m' gives the contourto the iinished screw, is moved toward the blank by the wedge, and awayfrom it by the tool or some piece moving with the tool, or it may bemoved away by a spring or a connection with the wedge or other movingpart of the machine.

An inclined plane, u, is attached to a sliding rod, a', pressed downwardby a spring, a?, and this inclined plane rests upon the cam g2, andabuts against one end of a rod, o, which is free both to rock and slidein standards attached to the bed-plate. A spring, o', forces this rodagainst the' inclined plane, and the inclined plane, being caused torise and descend by means of the cam and spring, causes the rod o, to.move to and fro parallel to the axis of the screw-blank, or nearly so.

Upon the rod o is mounted the tool-post or chaser holder p, carrying thetool or chaser pf, and also a guiding-pin or tracer p2, which is kept incontact with the acting face of the mold m by means of the spring p3.

When ascrew-blank is inserted in the chaps, the bearing-piece ot' thehanger rests in the deep and long depression of thc cam 7a2, as at 7c3,the wed ge bein g then thrown back by the spring t2, and the mold beingforced away from the screw-blank by the spring p3, acting through theintervention of the tool-post and tracer, the chaser itself beingtherefore ont of contact with the blank and free to travel in directionsfrom its point to its head, and vice versa, without touching the blank.

As the cam k2 revolves, it commences to force the wedge in the directionof its point, and when the chaser is opposite that part of the blankwhere the thread commences, the wedge has forced the mold or former sonear the blank that the tool governed by it commences to cut, beingcarried toward the point of the screw by the inclined plane u, andforced toward the axis of thescrew by the mold, wedge, and cam k2. When011e cutis iinished, the hanger drops into a depression of the cam, thewedge approaches the cam, the mold recedes from the blank, and the tool,no longer kept up to its work by the mold and freed from the control ofthe inclined plane n, is forced, by the spring o, back again to thepoint of commencement of the screw-thread. The cam k?, as it continuesto revolve, again forces the Wedge in the direction of its point, asbefore, again carrying the mold against the tracer and the tool againstthe blank, and this latter is then chased deeper than before, owin gtothefact that the wedge is forced farther toward its point on account ofthe shape of the cam. After this second cut is finished, the hangerdrops into a succeeding depression and the tool recedes away from theblank and retreats toward its head, ready to commence the third cut,which is deeper than the second. Successive cuts are thus made until thethread on the screw is completed.

1t is deemed unnecessary to give any special description of sizes ofgearing or shape of cams, or the depth of successive cuts, or the numberthereof', as all these points are well known to makers of screw-threading machinery. Yet I do deem it necessary to state that the screwblank maybe held and revolved in any known or proper manner; that the chaser maybe mounted as described, or in any proper way so long as it can be movedin di-,` rections both parallel and perpendicular to the screw-blank,and that it may be forced to travel parallel to orin the direction ofthe axis of the blank by means of al1 inclined plane or a cam, a comb,or a leading-screw. I also deem it necessary to state that the wedgecontrolling the mold or former may be governed by a cam mounted upon anaxis perpendicular to the line ofmotion of the wedge, instead ofparallel to it, as shown in the drawings; and, further, that the wedgemay be moved in both directions by the cani or in one direction only,and in the other direction by any suitable spring, or a motion derivedfrom some moving partof the machine; butin all cases acam must withaccuracy for any given diameter of blank by simply changing the positionofthe hanger in relation to the point of the wedge. It is also obviousthat the depths of successive cuts may be decreased or increased byusing wedges of greater or less inclinationin connection with moldsvaried in shape to iit the inclination of thewedge, and I intend toprovide for such substitution of wedges without changing the mold by soconstructing the same that the face upon which the Wedge bearsisadjustable with respect to the acting face of the mold.

I amaware of the fact that cams have been used to control the successivecuts of a chaser both directly and through the intervention of othermechanical devices. I am also acquaint ed with the fact that a mold orformer is an old device in screw-threading machinery, and that it hasbeen caused to approach and recede from the blank by various mechanicalappliances.

I therefore claim as of my own invention only- The combination of a cam,a wedge, and a mold or former, constructed and operating to control achaser or threading-tool in its motions perpendicular to the axis of theblank, or nearly so, substantially in the manner hereinbefore described.

In testimony whereof' I have hereunto subscribed my name.

H. A. HARVEY.

In presence oti- Gno. W. PENWARDEN, CHAs. BLrvEN.

